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I-Capacitors yenye yezona zinto zisetyenziswa ngokuqhelekileyo kwiibhodi zeesekethe. Njengoko inani lezixhobo zombane (ukusuka kwiifowuni eziphathwayo ukuya kwiimoto) liqhubeka nokunyuka, kunjalo ke imfuno ye-capacitors. Ubhubhani we-Covid-19 uphazamise ikhonkco lobonelelo lwecandelo lehlabathi ukusuka kwii-semiconductors ukuya kumacandelo asebenzayo, kwaye ii-capacitors bezinqongophele1.
Iingxoxo ngesihloko se-capacitors zinokuguqulwa ngokulula zibe yincwadi okanye isichazi-magama. Okokuqala, kukho iintlobo ezahlukeneyo ze-capacitors, ezifana ne-electrolytic capacitors, i-film capacitors, i-ceramic capacitors kunye nokunye. Emva koko, kuhlobo olufanayo, kukho izinto ezahlukeneyo ze-dielectric. Kukho neeklasi ezahlukeneyo. Ngokubhekiselele kwisakhiwo somzimba, kukho iindidi ezimbini ze-terminal kunye ne-threminal capacitor. Kukwakho nohlobo lwe-X2Y capacitor, eyona peri ye-Y capacitors efakwe kwenye. Kuthekani ngee-supercapacitors? Inyani yile, ukuba uhlala phantsi kwaye uqale ukufunda izikhokelo zokukhetha i-capacitor ezivela kubavelisi abakhulu, unokuchitha usuku ngokulula!
Ekubeni eli nqaku limalunga neziseko, ndiya kusebenzisa indlela eyahlukileyo njengesiqhelo. Njengoko kukhankanyiwe ngaphambili, izikhokelo zokukhetha i-capacitor zinokufumaneka ngokulula kwiiwebhusayithi zababoneleli be-3 kunye ne-4, kwaye iinjineli zentsimi zihlala ziphendula imibuzo emininzi malunga ne-capacitors. Kweli nqaku, andiyi kuphinda into ongayifumana kwi-Intanethi, kodwa iya kubonisa indlela yokukhetha nokusebenzisa i-capacitors ngemizekelo ebonakalayo. Eminye imiba engaziwayo kakhulu yokukhetha i-capacitor, njengokuthotywa kwe-capacitance, nayo iya kugutyungelwa. Emva kokufunda eli nqaku, kufuneka ube nokuqonda kakuhle ukusetyenziswa kwee-capacitors.
Kwiminyaka eyadlulayo, xa ndandisebenza kwinkampani eyenza izixhobo ze-elektroniki, sasinombuzo wodliwano-ndlebe nenjineli yombane. Kumzobo wesicwangciso semveliso ekhoyo, siya kubuza abantu abanokuba ngabagqatswa "Yintoni umsebenzi we-DC link electrolytic capacitor?" kwaye "Yintoni umsebenzi we-ceramic capacitor ebekwe ecaleni kwetshiphu?" Siyathemba ukuba impendulo echanekileyo yi-DC bus capacitor Isetyenziselwa ukugcina amandla, i-ceramic capacitors isetyenziselwa ukucoca.
Impendulo "echanekileyo" esiyifunayo ngokwenene ibonisa ukuba wonke umntu kwiqela loyilo ujonga i-capacitors ukusuka kumbono wesekethe olula, kungekhona kwimbono yethiyori yentsimi. Imbono ye-theory yesekethe ayilunganga. Kwii-frequencies ezisezantsi (ukusuka kwi-kHz ezimbalwa ukuya kwi-MHz embalwa), ithiyori yesekethe idla ngokuchaza ingxaki kakuhle. Oku kungenxa yokuba kwiifrikhwensi ezisezantsi, umqondiso ikakhulu ukwimowudi yokwahlula. Ukusebenzisa i-theory yesekethe, sinokubona i-capacitor eboniswe kwi-Figure 1, apho i-requivalent series resistance (ESR) kunye ne-series series inductance (ESL) yenza ukuba i-impedance ye-capacitor iguqule ngokuphindaphindiweyo.
Lo mzekelo uchaza ngokupheleleyo ukusebenza kwesiphaluka xa isiphaluka sitshintshwa ngokukhawuleza. Nangona kunjalo, njengoko ixesha likhula, izinto ziya zisiba nzima ngakumbi. Ngexesha elithile, icandelo liqala ukubonisa ukungahambisani nomgca. Xa i-frequency inyuka, imodeli ye-LCR elula inemida yayo.
Namhlanje, ukuba ndibuzwe umbuzo ofanayo wodliwano-ndlebe, ndiza kunxiba iiglasi zam zokujonga ithiyori yentsimi kwaye nditsho ukuba zombini iintlobo ze-capacitor zixhobo zokugcina amandla. Umahluko kukuba i-electrolytic capacitors inokugcina amandla amaninzi kune-ceramic capacitors. Kodwa malunga nokuhanjiswa kwamandla, i-ceramic capacitors inokuhambisa amandla ngokukhawuleza. Oku kuchaza ukuba kutheni i-ceramic capacitors kufuneka ibekwe ecaleni kwe-chip, kuba i-chip ine-frequency ephezulu yokutshintsha kunye nesantya sokutshintsha xa kuthelekiswa nombane oyintloko.
Ngokwale mbono, sinokuchaza ngokulula imigangatho emibini yokusebenza kwee-capacitors. Enye kukuba amandla angakanani i-capacitor enokuyigcina, kwaye enye yindlela ngokukhawuleza la mandla anokudluliselwa ngayo. Zombini zixhomekeke kwindlela yokuvelisa i-capacitor, i-dielectric material, ukudibanisa kunye ne-capacitor, njalo njalo.
Xa ukutshintshwa kwisekethe kuvaliwe (jonga uMzobo 2), kubonisa ukuba umthwalo udinga amandla avela kumthombo wamandla. Isantya apho olu tshintsho luvala khona lumisela ukungxamiseka kwemfuno yamandla. Ekubeni amandla ehamba ngesantya sokukhanya (isiqingatha sesantya sokukhanya kwizinto ze-FR4), kuthatha ixesha lokudlulisa amandla. Ukongeza, kukho ukungahambelani kwe-impedance phakathi komthombo kunye nomgca wothumelo kunye nomthwalo. Oku kuthetha ukuba amandla angeke adluliselwe kuhambo olunye, kodwa kwiihambo ezininzi ezijikelezayo5, yiyo loo nto xa utshintsho lutshintshwa ngokukhawuleza, siya kubona ukulibaziseka kunye nokukhala kwi-wave wave wave.
Umfanekiso 2: Kuthatha ixesha ukuze amandla asasazeke esithubeni; ukungahambelani kwe-impedance kubangela iihambo ezininzi ezijikelezayo zokudluliselwa kwamandla.
Inyaniso yokuba ukuhanjiswa kwamandla kuthatha ixesha kunye neehambo ezininzi ezijikelezayo zisixelela ukuba kufuneka sihambise amandla ngokusondeleyo kangangoko kunokwenzeka kumthwalo, kwaye kufuneka sifumane indlela yokuyihambisa ngokukhawuleza. Eyokuqala idla ngokufezekiswa ngokunciphisa umgama womzimba phakathi komthwalo, ukutshintsha kunye ne-capacitor. Le yokugqibela iphunyezwa ngokuqokelela iqela le-capacitors kunye ne-impedance encinci.
Ithiyori yendawo ikwachaza ukuba yintoni ebangela ingxolo yemowudi eqhelekileyo. Ngamafutshane, ingxolo yemowudi eqhelekileyo yenziwa xa imfuno yamandla yomthwalo ingafezekiswanga ngexesha lokutshintsha. Ngoko ke, amandla agcinwe kwisithuba phakathi komthwalo kunye nabaqhubi abasondeleyo baya kunikwa ukuxhasa imfuno yesinyathelo. Isithuba phakathi komthwalo kunye nabaqhubi abasondeleyo yinto esiyibiza ngokuba yi-parasitic / mutual capacitance (jonga uMzobo 2).
Sisebenzisa le mizekelo ilandelayo ukubonisa indlela yokusebenzisa i-electrolytic capacitors, i-multilayer ceramic capacitors (MLCC), kunye nefilimu capacitors. Zombini i-theory kunye ne-field theory zisetyenziselwa ukuchaza ukusebenza kwee-capacitors ezikhethiweyo.
Ii-electrolytic capacitors zisetyenziswa ikakhulu kwikhonkco le-DC njengomthombo wamandla oyintloko. Ukukhetha i-electrolytic capacitor ihlala ixhomekeke koku:
Ukusebenza kwe-EMC, ezona mpawu zibalulekileyo ze-capacitors ziyi-impedance kunye neempawu zokuphindaphinda. Ukukhutshwa okuphantsi okuqhutywa rhoqo kuxhomekeke ekusebenzeni kwe-DC link capacitor.
I-impedance ye-DC link ayixhomekanga kuphela kwi-ESR kunye ne-ESL ye-capacitor, kodwa nakwindawo ye-thermal loop, njengoko kuboniswe kuMzobo 3. Indawo enkulu ye-thermal loop ithetha ukuba ukuhanjiswa kwamandla kuthatha ixesha elide, ngoko ukusebenza iya kuchaphazeleka.
I-step-down converter ye-DC-DC yakhiwe ukubonisa oku. Ukusetwa kovavanyo lwe-EMC kwangaphambili oluboniswe kuMzobo 4 lwenza iskena sokukhutshwa kokukhutshwa phakathi kwe-150kHz kunye ne-108MHz.
Kubalulekile ukuqinisekisa ukuba ii-capacitors ezisetyenzisiweyo kulo mzekelo zivela kumvelisi ofanayo ukuphepha ukungafani kweempawu ze-impedance. Xa uthengisa i-capacitor kwi-PCB, qiniseka ukuba akukho zikhokelo ezinde, njengoko oku kuya kwandisa i-ESL ye-capacitor. Umzobo 5 ubonisa ulungelelwaniso oluthathu.
Iziphumo ezikhutshwayo eziqhutywayo zolu lungelelwaniso zithathu zibonisiwe kuMfanekiso 6. Ingabonwa ukuba, xa kuthelekiswa ne-680 µF capacitor enye, ii-capacitor ezimbini ze-330 µF zifezekisa ukusebenza kokunciphisa ingxolo ye-6 dB kuluhlu lwamaza obubanzi obubanzi.
Ukususela kwi-theory yesekethe, kunokuthiwa ngokudibanisa i-capacitors ezimbini ngokufanayo, zombini i-ESL kunye ne-ESR zisiqingatha. Ukusuka kwimbono yethiyori yentsimi, akukho mthombo wamandla omnye kuphela, kodwa imithombo yamandla emibini inikezelwa kumthwalo ofanayo, ngokufanelekileyo ukunciphisa ixesha lokuhambisa amandla ngokubanzi. Nangona kunjalo, kwiifrikhwensi eziphezulu, umahluko phakathi kwee-capacitor ezimbini ze-330 µF kunye ne-680 µF capacitor enye iya kuncipha. Oku kungenxa yokuba ingxolo ephezulu ibonisa ukungonelanga kwempendulo yamandla. Xa uhambisa i-330 µF capacitor kufuphi nokutshintsha, sinciphisa ixesha lokudlulisa amandla, okwandisa ngokufanelekileyo impendulo yesinyathelo se-capacitor.
Umphumo usixelela isifundo esibaluleke gqitha. Ukwandisa i-capacitance ye-capacitor eyodwa ngokuqhelekileyo ayiyi kuxhasa imfuno yesinyathelo samandla amaninzi. Ukuba kunokwenzeka, sebenzisa amanye amacandelo amancinci e-capacitive. Kukho izizathu ezininzi ezifanelekileyo zoku. Eyokuqala ziindleko. Ngokuqhelekileyo, ubungakanani bepakethe efanayo, ixabiso le-capacitor liyakhula ngokukhawuleza ngexabiso le-capacitance. Ukusebenzisa i-capacitor enye kunokubiza kakhulu kunokusebenzisa ii-capacitor ezininzi ezincinci. Isizathu sesibini bubukhulu. Into ethintelayo kuyilo lwemveliso ngokuqhelekileyo ukuphakama kwamacandelo. Kwi-capacitors yomthamo omkhulu, ukuphakama kudla ngokuba kukhulu kakhulu, okungafanelanga ukuyila imveliso. Isizathu sesithathu yintsebenzo ye-EMC esiyibonile kwisifundo sophononongo.
Enye into ekufuneka uyiqwalasele xa usebenzisa i-electrolytic capacitor kukuba xa uqhagamshela ii-capacitors ezimbini kuthotho ukwabelana nge-voltage, uya kufuna i-bancing resistor 6.
Njengoko kuchaziwe ngaphambili, i-ceramic capacitors zixhobo ezincinci ezinokunika amandla ngokukhawuleza. Ndihlala ndibuzwa umbuzo othi "Ingakanani i-capacitor endiyifunayo?" Impendulo yalo mbuzo kukuba i-ceramic capacitors, ixabiso le-capacitance akufanele libaluleke kangako. Uqwalaselo olubalulekileyo apha kukuqinisekisa ukuba isantya sogqithiso lwamandla sikwanela kangakanani isicelo sakho. Ukuba ukukhutshwa okuqhutywayo akuphumeleli kwi-100 MHz, ngoko i-capacitor ene-impedance encinci kwi-100 MHz iya kuba yinto efanelekileyo.
Oku kokunye ukungaqondi kakuhle kwe-MLCC. Ndibone iinjineli zichitha amandla amaninzi zikhetha i-ceramic capacitors ene-ESR ephantsi kunye ne-ESL ngaphambi kokuqhagamshela i-capacitors kwindawo yereferensi yeRF ngokusebenzisa umkhondo omde. Kuyafaneleka ukukhankanya ukuba i-ESL ye-MLCC ihlala iphantsi kakhulu kune-inductance yokudibanisa ebhodini. I-inductance yoqhagamshelo iseyeyona parameter ibaluleke kakhulu echaphazela i-impedance ephezulu ye-ceramic capacitors7.
Umzobo 7 ubonisa umzekelo ombi. Umkhondo omde (0.5 intshi ubude) wazisa ubuncinci be-10nH inductance. Isiphumo sokulinganisa sibonisa ukuba i-impedance ye-capacitor iba phezulu kakhulu kunokuba ilindeleke kwi-frequency point (50 MHz).
Enye yeengxaki ngee-MLCCs kukuba zikholisa ukunxulumana nolwakhiwo lwe-inductive ebhodini. Oku kunokubonwa kumzekelo oboniswe kuMfanekiso 8, apho ukusetyenziswa kwe-10 µF MLCC yazisa iresonance malunga ne-300 kHz.
Unokunciphisa i-resonance ngokukhetha icandelo kunye ne-ESR enkulu okanye ukubeka nje i-resistor encinci yexabiso (njenge-1 ohm) kwichungechunge kunye ne-capacitor. Olu hlobo lwendlela lusebenzisa amacandelo alahlekileyo ukucinezela inkqubo. Enye indlela kukusebenzisa elinye ixabiso le-capacitance ukuhambisa i-resonance kwindawo ephantsi okanye ephezulu ye-resonance.
I-Film capacitors isetyenziswa kwizicelo ezininzi. Zizo ii-capacitors ezikhethiweyo zamandla aphezulu e-DC-DC converters kwaye zisetyenziswa njengezihluzo zocinezelo ze-EMI kuzo zonke iintambo zamandla (AC kunye ne-DC) kunye noqwalaselo lwendlela eqhelekileyo yokucoca. Sithatha i-X capacitor njengomzekelo ukubonisa ezinye zeengongoma eziphambili zokusebenzisa i-filimi capacitors.
Ukuba isiganeko sotyando senzeka, kunceda ukunciphisa uxinzelelo lombane oluphezulu kumgca, ngoko ke ngokuqhelekileyo lusetyenziswa kunye ne-transient voltage suppressor (TVS) okanye i-metal oxide varistor (MOV).
Usenokuba sele ukwazi konke oku, kodwa ngaba ubusazi ukuba ixabiso le-capacitance ye-X capacitor linokuncipha kakhulu ngeminyaka yokusetyenziswa? Oku kuyinyani ngakumbi ukuba i-capacitor isetyenziswe kwindawo efumileyo. Ndiyibonile ixabiso le-capacitance ye-X capacitor lehla kuphela kwiipesenti ezimbalwa zexabiso layo elilinganisiweyo phakathi konyaka okanye emibini, ngoko ke inkqubo eyilwe ekuqaleni kunye ne-X capacitor ilahlekelwe lukhuseleko olunokuthi lube nalo.
Kwenzeka ntoni ke? Umoya omanzi unokuvuza kwi-capacitor, phezulu ucingo naphakathi kwebhokisi kunye ne-epoxy potting compound. I-metalization ye-aluminiyam inokuthi ifakwe i-oxidized. I-Alumina yinto efanelekileyo yokukhusela umbane, ngaloo ndlela inciphisa i-capacitance. Le yingxaki apho bonke abaxhasi befilimu baya kuhlangana nabo. Umba endithetha ngawo bubunzima befilimu. Iimpawu ze-capacitor ezihloniphekileyo zisebenzisa iifilimu ezityebileyo, ezikhokelela kwii-capacitors ezinkulu kunezinye iimpawu. Ifilimu encinci yenza i-capacitor ingabi namandla okugqithisa (i-voltage, yangoku, okanye iqondo lokushisa), kwaye akunakwenzeka ukuba iziphilise.
Ukuba i-X capacitor ayidityaniswanga ngokusisigxina kunikezelo lwamandla, ngoko awudingi ukuba nexhala. Ngokomzekelo, kwimveliso enokutshintsha okunzima phakathi kokunikezelwa kwamandla kunye ne-capacitor, ubukhulu bunokubaluleka kunobomi, kwaye ke unokukhetha i-capacitor encinci.
Nangona kunjalo, ukuba i-capacitor ixhunyiwe ngokusisigxina kumthombo wamandla, kufuneka ithembeke kakhulu. I-oxidation ye-capacitors ayinakuphepheka. Ukuba i-capacitor epoxy impahla isemgangathweni kwaye i-capacitor ayisoloko ibonakaliswe kumaqondo okushisa aphezulu, ukuhla kwexabiso kufuneka kuncinci.
Kweli nqaku, kuqala yazisa imbono yethiyori yentsimi yee-capacitors. Imizekelo esebenzayo kunye neziphumo zokulinganisa zibonisa indlela yokukhetha nokusebenzisa iintlobo ze-capacitor eziqhelekileyo. Ndiyathemba ukuba olu lwazi lunokukunceda uqonde indima yee-capacitors kuyilo lwe-elektroniki kunye ne-EMC ngokubanzi.
UGqr. Min Zhang ungumseki kunye nomcebisi oyintloko we-EMC we-Mach One Design Ltd, inkampani yobunjineli yase-UK egxile kwi-EMC Consulting, ukulungisa iingxaki kunye noqeqesho. Ulwazi lwakhe olunzulu kumandla ombane, i-elektroniki yedijithali, iimotor kunye noyilo lwemveliso luncede iinkampani emhlabeni jikelele.
Ukuthobela ngowona mthombo weendaba, ulwazi, imfundo kunye nenkuthazo yeengcali zobunjineli bombane kunye ne-elektroniki.
I-Aerospace Automotive Communications Consumer Electronics Education Amandla kunye ne-Power Industry Information Technology Technology kwi-Meditary Medical and National Defense